Electric heater



Oct. v

1,512,209 "r. s. FULLER ET AL ELECTRIC HEATER Filed Aug. 24. 1921 Inventors Truman SFuller, and John-A.Wat'd.

Their Attorney Patented Oct. 21, 1924.

UNITED STATES PATENT OFFICE- TRUMAN S. AND JOHN A.,WARD, OF SCHENECTADY, NEW YORK, ASSIGNORS TO GENERAL ELECTRIC COMPANY, A. CORPORATION OF NEW YORK.

ELECTRIC HEATER.

Application filed August 24, 1921. Serial No. 194,941.

' lowing is a specification.

This invention relates to electric heaters and has for its object the provision of improved means for automatically opening the circuit of the heater at a predetermined temperature.

More specifically, our invention relates to electric fiat-irons in which a thermostatic element is provided for automatically operating a switch in the heating circuit to prevent excessive temperatures in the flat-iron. In carrying out our invention, we employ a helical thermostatic element which is mounted in a recess within the heated body of the flat-iron. On top of the body of the flatiron we mount a switch in the heating circuit which is operatively connected to the thermostatic element so as to be opened upon the occurrence of a predetermined maximum temperature. The operative connection between the thermostatic element and the switch is provided with an adjustment which can be set to cause the switch to be opened at the desired maximum temperature.

In the accompanying drawing, Fig. 1 shows a fiat-iron constructed in accordance with our invention with the principal parts in spaced relation; Fig. 2 is a diagrammatic representation of the heating circuit and automatic cut-out; Fig. 3 is a' plan view of the electric switch in the heating circuit;

Fig. 4 is a view in perspective of the spring latch for the switch; Fig. 5 is a view in perspective of the movable switch arm; Fig. 6'

1s a, view in perspective of the stationary parts of the switch; Fig. 7 is a view in perspective of the operative connection between the thermostatic element and the switch, while Fig. 8 is a section along the line 88 of Fig. 6 looking in the' direction of the arrows.

Referring to the drawing, the flat-iron 10 comprises a heated body consisting of a metallic sole plate 11 and a metallic pressure plate 12, and a cover 13 provided with a handle (not shown). The pressure plate 12 is adapted to be securedto "the sole plate 11 with a suitable heating element 14 clamped between. The heating element is insulated between two sheets of mica, and'is provided with terminals 15 and 16.. The cover 13 fits over pressure plate 12 onto sole plate 11, the parts being secured together by suitable screws.

In the sole plate 11 is an elongated recess 17 in which is mounted ahelical thermostatic element 18. The thermostatic element is mounted in spaced relation with the walls of the recess by means of a rod 19 which extends through the thermostatic element and is rigidly secured thereto at one end. The opposite end of the rod 19 is attached by means of a screw 19 to the plate 11. The thermostatic element is thus mounted so that it can freely rotate about rod 19 in response to changes of temperature. The free end 20 of the thermostatic element extends at right angles to rod 19 into a transverse intersecting recess 21. I o

The switching mechanism for the heating circuit is mounted on top of pressure plate 12 upon a metallic supporting plate 22, which is secured in parallel spaced relation to the pressure plate by means of three downturned projections .23, 24 and 25 formin legs. A U-shaped stri of metal 26 provide with two projections 2 and 27 is secured by means of a rivet to the right hand end of plate 22 and maintained in insulated'relation to the plate by means of a strip of insulating material 26. Projection 27 extends upwardly and bears a stationary contact 28, while projection 27 extends downwardly and is provided with a screw so as to form a convenient connection terminal for contact 28. A second U-shaped strip. of metal 30 is secured in like manner in insulated relation to plate 22 and in spaced relation with contact 28. Strip 30 has an upwardly turned projection carrying a contact 31. The other end of strip 30 is folded back, as shown in Fig. 8, bent downwardly and provided with a screw to form a convenient connection terminal 32 for contact 31. Cooperating with stationary contacts 28 and 31 are two movable contacts 33 and 3 1 which are secured to opposite ends of a resilient metallic strip 35. The strip 35 is secured at at its middle by means of rivets to a switch arm 36 and insulated from arm 36 by strips of insulating material Switch arm 36 is I secured at one end by a screw 37 to plate 22 so as to be movable about screw 37 as an axisto bring contacts 33 and 34 into engagement in Fig. ito have a latching projection 43 near one end and a right angle extension 44:. The latch l2 has its longer end se-.,

cured to plate 22 so that projection 43 eX- tends normally through .a rectangular opening ie in the plate and projects slightly above it. a right angle member 46 having an opening 4:? therethrough. The member 46 rests on plate 22 so that opening at is above opening 45 in the plate. When switch arm 36 is moved to closecircuit position, member 46 slips aver projection 43 forcing it downward until it springs into opening t7 and engages member 46 so as to hold the switch arm titi in closed position. engages with latch 12, slides beneath an over- P hanging strip d8 secured to plate 22 and in this manner is held downward onto plate 22 against the pressure of latch 42 while passing over the projection 43.

Latch 4:2 is operatively connected to the "thermostatic element 18 by means of a lever arm 4;) which is pivotally supported on a braclret 50 secured to the lower side of plate 22, the point of support of lever arm 49 being nearer the left hand end. The lever arm is supported in a rectangular opening 51 in the pressure plate, the right hand end oi the lever arm being curved downwardly through the opening. The left hand end oi the lever arm is connected by means of a suitable link 4:3 to the extension at on latch 4.2, while to the right hand end of thelever arm is secured a screw 52 having a lock nut 53 by means ot which the screw may be tightened in any adjusted position. When the pressure plate 12 is assembled on the sole plate ll, screw 52 is directly above and inposition to be engagedby the tree end 20 of the thermostatic element. By means of arm at) the thermostatic element is given an increased leverage in tripping latch 42. The operation or the thermostatic element is therefore both positive and sensitive. Se cured to aprojection 55 on switch arm 36 is.a push-lontton56 whiph is adapted to extend through an opening 57 in the cover 13 Integral with switch arm 36 is.

The member 46, as it neiaaoe when the fiat-iron is assembled. lit will be observed that the switching mechanism is inclosed by the cover 13. p

Terminal 15 of the heating element is connected permanently tothe connection 27, while terminal 16 is connected to main 58 leading to a suitable source of electric supply, the opposite side of which is connected through main 59 to terminal 32.

As thus constructed and arranged the operation of our invention is as follows: When it is desired to heat the iron, button 56 is pressed inward until switch arm 36 is moved to closed circuit position and locked by latch 4:2. A circuit for heating element It is thus closed from supply main .58 through the heating element, contacts 28 and 34, metallic strip 35, and contacts 33 and 31 to supply main 59. The flat-iron now heats u and transmits its heat to the thermostatic e ement. As the temperature or the tlatiron increases the thermostatic element is afl'ected torotate its free end 20 upwardly about rod 19, and at some predetermined maximum temperature arm 20 will engage screw 52 and give it suficient upward movement to move projection-4e3 downward and release switch arm 36, which moves about its pivot due to the influence or spring 38, thus opening the heating circuit through the contacts. In order to again heat the fiatiron the heating circuit must be reclosed manually by pressing button 56, previously described. By adjusting the posi tion of screw 52, the switching mechanism can be set to open the heating circuit at the desired maximum temperature.

lit will be observed that we have provided very simple, reliable, and economical means, for automatically opening the heating circult of a fiat-iron in response to excessive temperature. The coiistruction is suchas to cause a quick break and thereby. prevent injurious arcing at the. contacts. The thermostatic element is mounted within the Mill heated body of the fiat-iron near the ironing a lace and is consequently immediately responsive to the temperature of the heated body and particularly to the temperature of:

the ironing face, which is the part of the mechanism and the "operative connection with the thermostatic element on a single pp r wh ch isattached to the body f the flat-iron provides for simplicity and. economy in manufacture. ,7 The necessity for extremely accurate name work. in. the

various parts of the switching mechanism, the thermostatic element, and the flat-iron is avoided by means of our adjustable operative connection between the thermostatic element and the switching mechanism.

In accordance with the provisions of the patent statutes, we have described the principle of operation of our invention, together with the apparatus which we now consider to represent the best embodiment thereof, but we desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other means. c

lVhat we claim as new and desire to secure by Letters Patent of the United States, is,

l. A temperature cut-out for electric heaters comprising in combination with a heated body, a thermostatic element within said body, a supporting plate mounted on said body .in spaced relation thereto, stationary and movable switch contacts mounted on said plate, a spring for biasing said movable switch contact to open circuit position, a latch secured to said plate arranged to hold said movable switch contact in closed circuit position, and a lever arm secured to said plate having one end cooperating with said latch and the other end cooperating with said thermostatic element so as to be actuated by said thermostatic element to release said movable switch contact upon the occurrence of a predetermined tempera ture.

2. A temperature cut-out for electric heaters comprising in combination with a heated body, a thermostatic element supported within said body, a supporting plate mounted on said body in spaced relation thereto, a pair of stationary insulated switch contacts in the circuit of said heater carried by said plate, a switch arm pivotally insulated therefrom, a pair of movable contactsadapted to cooperate with said stationary contacts carried by said resilient member, a latch secured to said plate and adapted to engage said switch arm to-hold it in closed position, and a lever arm secured to said plate-having one end coop- 'erating with said latch and the other end cooperating with the thermostatic element, whereby the latch is strip ed by the thermostatic element to open the circuit of said heater upon the occurrence of a predetermined temperature.

3. An electric flat-iron comprising a sole plate, a heating element therefor, a thermostatic element in thermal relation with said sole plate, a pressure plate above said sole plate, switch mechanism on said pressure plate having an opening to said sole plate, and operative connections from the thermostatic element to the switch mech- .a lever arm having one end cooperating with said latch and the other end extending through said aperture and cooperating wit said thermostatic element, whereby the switch is released to open the circuit of said heating element upon the occurrence of a predetermined temperature.

In witness whereof, we have hereunto set our hands this twenty-third day of August, 1921.

TRUMAN S. FULLER. JOHN A. WARD. 

